1. FIELD OF THE INVENTION
The invention relates to a coolable furnace wall structure having a steel shell and a refractory lining inside the shell, for example for a blast furnace.
2. DESCRIPTION OF THE PRIOR ART
To cool such a furnace wall, it is known to insert cooling plates into the wall. At regular intervals, openings are made in the shell and corresponding recesses are provided behind them in the lining, into which the cooling plates, which are hollow plate-shaped elements, extend. The cooling plates are removably connected to the shell and fitted with supply and discharge openings for cooling liquid. Such a wall structure is often used in shaft furnaces, in particular in blast furnaces, but the applicability of the present invention is not limited to these installations.
In particular, in a blast furnace the cooling plates are used to remove heat from the inside of the furnace, in order to prevent overheating of the lining and the steel shell. In addition, the cooling plates, which mostly consist of cast copper, have a supporting function, in order to limit the relative movement of the lining and the shell.
In modern high-capacity blast furnaces which are operated under over-pressure, the cooling plates need to be fixed to the shell so that they are gastight, for which purpose either flanged connections or welded connections are used.
One drawback to the known structure described above is that the shell is weakened at many points by the openings. The structure which is often used in practice and is sufficiently strong, is the result of balancing on the one hand the costs of a much thicker shell structure and on the other hand the use of fewer cooling plates, which means that less cooling than ideally is desired has to suffice. Particularly where a blast furnace is operated at high production rate, the cooling capacity required makes an extra thick and hence expensive shell structure necessary. When modernizing an existing blast furnace installation, one is very often tied to the shell structure present. An increase in the cooling capacity by the fitting of extra cooling plates has the drawback that this would result in an inadmissible weakening of the shell.